A variety of emulsifying agents including imidazolines have been proposed and used in oil based drilling fluids. In U.S. Pat. No. 4,374,737, a drilling fluid composition is disclosed containing diethanolamide, a fatty acid, an imidazoline/amide mixture and a non-polluting oil. Stable water-in-oil emulsions that are proposed for use in oil well drillmuds are described in U.S. Pat. No. 3,728,277 as an admixture comprising (a) an imidazoline or oxazoline salt of a long chain fatty acid and (b) a salt of a long chain aliphatic amido amine and a long chain aliphatic carboxylic acid. U.S. pat. No. Re. 23,277 discloses a variety of imidazoline compounds that are said to inhibit the corrosion of metals in oil wells by corrosive oil or oil-brine mixtures. Included in the group of specific imidazolines disclosed are 2-oleylimidazoline and 1-oleoloxyethyl,2-ethylimidazoline. Derivaties of imidazoline and pyrimidine demulsifiers that are useful in breaking petroleum emulsions of the water-in-oil type obtained by the reaction between a polycarboxylic acid and highly oxypropylated substituted imidazolines and pyrimidines, are disclosed in U.S. Pat. No. 2,713,582.